1. Technical Field of the Invention
The present invention relates to a matched filter acting in charge domain which can be used for a communication apparatus, a signal processing equipment or the like.
2. Prior Art
As the result of digital technology development, CMDA (Code Division Multiple Access) communication or other digital modulation methods are becoming popular rapidly; however the function required to the system is attaining such a high level that it can be hardly realized with conventional methods using digital processing in respect of system size or power consumption and this problem has became already evident in power supply limited applications such as portable terminals.
As an approach for solving these problems, new methods introducing analog processing such as Japanese Patent Laid-Open No. Hei 6-164320 are being developed, sloughing off ineffective power consumption inherent to conventional digital signal processing.
However, one can hardly affirm that these methods allow to realize a large-scale analog shift register corresponding to future enlargement of modulation code, or to establish so far a technology which would be able to correspond for a long term to commercialization constrictions such as further reduction of power consumption.
The present invention intends to compose a charge mode operation circuit dedicated to detect the correlation between analog input signal and digital code using charge transfer devices such as CCD of which technology is already established, famous for its low power consumption, and moreover, to propose a charge mode operation circuit composition for realizing by "RAKE method" the path diversity reception from the correlation data obtained using the same.